Adjustable seat assembly



Se t. 1, 1953 E. w. M KNlGHT ADJUSTABLE SEAT ASSEMBLY Filed Sept. 5,1950 INVENTOR. EDGAR W- M06 KNIGHT HIS ATTORNEYS Patented Sept. 1, 1953UNITED STATES PATENT OFFICE ADJUSTABLE SEAT ASSEMBLY Edgar W. MacKnight,San Leandro, Calif.

Application September 5, 1950, Serial No. 183,245

6 Claims.

1 My invention relates to adjustable seats and more particularly to aseat assembly for techniclans such as dentists, to permit suchtechnicians to operate while comfortably seated, and constitutes animprovement upon the adjustable seat assembly forming the subject of myprior application for an Adjustable Seat Assembly, Serial No. 87,277,filed April 13, 1949, now Patent No. 2,572,874 of October 30, 1951.

Among the objects of my invention are:

(1) To provide a novel and improved adjustable seat assembly,particularly for use by dentists or the like when working on patients;

(2) To provide a novel and improved adjustable seat assembly fordentists or the like, which will facilitate the approach and retreat ofan operator with respect to a patient in a patients chair;

(3) To provide a novel and improved seat as-- sembly for dentists, whichwill permit such dentist Or the like to move with greater ease andcomfort to any desired position with respect to a patient;

(4) To provide a novel and improved seat assembly for dentists or thelike, which will permit movement by the operator to any desired positionwith respect to a patient, and afford such operator a stronger feelingof security while operating on such patient.

Additional objects of my invention will be brought out in the followingdescription of a preferred embodiment of the same taken in conjunctionwith the accompanying drawings wherein- Figure 1 is a view in section ofa seat assembly embodying the features of the present invention andillustrating the manner of tying the same in with a patients chair;

Figure 2 is a view in section, taken in the plane 2-2 of Figure 1;

Figure 3 is a view in section, taken in the plane 33 of Figure 2; and

Figure 4 is a view depicting a structural detail of the assembly ofFigure 1.

The invention, as illustrated in the drawings, includes a wheel truck 1involving a trough member 3 having depending side walls 5 and l, andbetween these side walls, adjacent each end of the trough member, thereis welded or otherwise afi'ixed a depending yoke 9 for mounting a wheelII.

A vertically disposed channel member I3, conwhich straddles the troughmember of the wheel 2 truck and is bolted thereto, thereby providingfirm anchorage for the vertical channel member.

This vertical channel supports a bracket IS on which a tongue 2| may beslidably adjusted as to elevation, such bracket constituting a pair ofspaced bracket blocks 22 and 23 inserted within the channel member andwelded or otherwise affixed thereto, and to the exposed ends of thesetwo blocks, there is bolted a bracket plate 25 of a width such that itsvertical edges extend slightly beyond the bracket blocks to either sidethereof.

The aforementioned tongue 2i involves a length of channel member,preferably slightly tapered for appearance sake, with it broad endtoward the bracket plate to which it is adjustably fixed for elevationaladjustments. This is accomplished by affixing to each side of the tongueat its broad end, a clamping plate 21 which overhangs or extends beyondthe end of the tongue suiiiciently to permit of the formation of agroove 29 adapted to receive an edge of the bracket plate. A clampingbolt 3| passing through the tongue and clamping plates constitutes meansfor drawing the clamping plates toward each other for clamping thetongue to the bracket plate at any desired position along such bracketplate.

Such vertical adjustment of the tongue permits the seat assembly to beaccommodated to chairs of diiferent designs and styles, as placed on themarket by different manufacturers, thus enabling the tongue to clearoperating pedals, engine rheostat, etc., as well as the base flange ofthe patient's chair, which allows the operator to move in close to thepatient.

At its narrow end, the tongue terminates in a pivot yoke 33 having itslegs lying in parallel horizontal planes, and perforated to receive avertically disposed clamping bolt 35.

The inner member of the telescopic standard constitutes a tube 31 whichcarries the seat 39 and associated mechanism 40. It is telescopicallysupported within the vertical channel member by providing alignedopenings in the bracket block 22, 23 of a size sufiiciently to slidablyreceive the tube, and at the upper end of the vertical channel member,there is provided means 43 for locking such tube in any verticallyadjusted position.

Such means comprises a rectangular housing of two sections, namely, alower section 45 which is integrally united to the upper end of thevertical channel member, and an upper section 41 which provides amatching fit with the lower section. The upper section is held to thelower section by a bolt 49, both section having vertically alignedopenings to permit passage of the tube 31.

Within the housing is a locking plate 5| which has a central beveledopening therethrough, through which the tube may comfortably pass whensuch locking plate is in a horizontal position. At one end, this lockingplate is loosely supported between a shoulder 53 and a flange 55 formedby suitably crimping a piece of sheet metal and welding the same intothe lower section of the housing, while at its opposite end, the plateis provided with a perforation through which the bolt 49 passes, theplate being normally urged downwardly at this end, against the tube 31by a compression spring 51 thereabove. Disposed below the locking platein line with the compression spring 51, is a lip 59 constituting one endof a lever 61, preferably in the form of a stiff wire loop which extendsthrough a wall of the housing and fulcrums on the edge of the openingthrough which it passes. Under the action of the compression spring, thetube will, in the absence of any opposing force, remain in itsprevailing adjustment, and any weight or pressure applied to the upperend of the tube, as when one sits upon the seat, will only serve toenhance the binding effect of the locking plate thereon.

When it is desired to adjust or change the elevational position of theseat which is carried on the tube, a downward pressure on the exposedand of the lever, will lift the lower end of the locking plate, therebybringing the plate to a horizontal plane, whereby the tube will be freedfor movement along its vertical axis.

As previously indicated, the tube 31 carries the seat 39 and itsassociated mechanism 40. Such associated mechanism includes a rod orshaft 63 iournaled in bearings 65, 61 disposed, one at each end of thetube. This shaft extends beyond the upper end of the tube and at thisend, there is fixedly mounted an arm 69 which terminates at its otherend in a bearing H, in which is journaled a short shaft I3 whichprotrudes from the hearing at either end thereof. At its upper end, thisshort shaft has affixed thereto a seat arm 15 in the free end of whichis journaled the stem 11 of a suitable seat 39, spaced bearings beingpreferably provided for this purpose.

As thus far described, the path of movement of the seat with respect tothe axis of the supporting tube, is indeterminable and not fixed. Thisis so because, under the circumstances, the seat is adapted to swingindiscriminately about the short shaft as an axis, while at the sametime, the short shaft is adapted to swing indiscrlminately about theaxis of the supporting tube. Therefore, in order to pre-establish thepermissible path of movement of the seat with respect to the axis of thesupporting tube, both of the aforementioned swinging movements must becontrolled with respect to each other.

This I accomplish by fixedly mounting on the upper end of the tube, asun gear 19, while at the lower end of the short shaft 13, I provide aplanetary gear Bl, and then connect the two gears by some drive meanssuch as a chain drive 83. With such a connection, any swinging movementon the part of the short shaft in an are about the axis of thesupporting tube, will cause the seat to swing in an arc in oppositedirection about the short shaft axis.

By selecting a proper relationship between the ratio of arm lengths andthe gear ratio, substantially linear movement of the seat may berealized and along a path through the axis of the supporting tube. Agear ratio of two to one between the sun gear and planetary gear willsatisfy the requirements, where both arms are of the same length.

To assure that such linear movement shall be confined to a particulardirection, namely, along the axis of the tongue, which will then providefor linear movement toward and away from a. patient, the seat and itsassociated mechanism should be initially assembled so that a linejoining the axis of the supporting tube and the center of the seat,shall sight along the axis of the tongue, and to assure maintenance ofsuch direc tional adjustment, the sun gear must be fixed againstrotation on its axis. This is accomplished by affixing a guide rib alongthe back of the bracket plate 25 and slidably engaging the same by aguide block 8'! aiiixed to the tube 31.

Extending upwardly from the sun gear, are a pair of stop pins B9, 91disposed on a line preferably slightly off center. Such stop pins standin the path of movement of the planetaryarm 69 and thus preclude theshort shaft from ever reaching a dead center P sition, which mightinterfere with smooth, effortless movement of the seat. Ease of movementof the seat between its forward and retracted positions will, therefore,always be assured.

A shroud 83 may be installed over the planetary gear arrangement and,when so installed, is held out of contact with the chain drive by a bolt95 extending through the planetary arm.

The entire seat assembly is designed for arcuate travel about the boltaxis located at the end of the tongue, and accordingly facilitate suchmovement, the truck wheel yokes 9 are installed on a slight angle so asto cause the wheels to describe an are about such pivot point withoutdrag.

Means for fastening the seat assembly to a dental chair preferably takesthe form of a pivot post I03, provision being made for anchoring thesame to the lower rim I05 of the base of the patients chair by means ofa suitable clamp. Such clamp may involve an arcuate trough section 109adapted to fit over the rim of the chair base, leaving an exposed upperhorizontal flange HI to which may be attached one end of the pivot post.

Such attachment is preferably by way of a ball and socket connection,the rim being raised at the point of connection to provide a socket H3,while the pivot post, at its point of connection, having a tubular lowerend H4 which is threaded internally for the reception of a bolt I I5passing through thejlange of the clamp, with its head fitting into thesocket. By constricting the neck of the belt, a certain latitude ofmovement for the pivot post will be permitted at this point.

By providing a lateral perforation through the lower end of the pivotpost to expose certain of the threads on the bolt. and then deformingsuch threads with a suitable tool, the pivot post connection to theclamp may be made permanent.

The pivot post is preferably made extensible by making it of telescopingparts. namely a pivoted tubular element H4 with a sleeve H9 slidablethereon, and then providing means for supporting the sleeve at differentelevational positions on the tubular element. This can be readilyaccomplished by laterally perforating the pivoted element at spacedpoints longitudinally, and providing a pair of diametrically disposedopenings in the sleeve, which are adapted to line up with selectedperforations in the pivoted element. The perforations in the sleeve arepreferably of larger diameter than the openings in the pivoted elementto receive the head and nut of a clamping bolt I23 passing through thealigned holes, whereby, upon tightening the nut on such bolt, thetightening pressure will be applied solely to the pivoted element, andsufficiently to compress the same and cause corresponding expansion in anormal direction against the sleeve, to thereby bind the same againstmovement with respect to the pivoted element.

At its upper end, the sleeve is closed except for a threaded axialopening for the reception oi the pin or bolt 35. Such bolt is adapted topass through the perforations in the yoke at the end of the tongue priorto threading the bolt into the upper end of the sleeve for securing theseat assembly to the pivot post. A suitable spacing collar I25 may beapplied to the bolt for disposition between the spaced arms of the pivotyoke, to rigidify the connection at this point, so that all pivotmovement will occur at the lower end of the pivot post.

The ball and socket pivot connection of the pivot post to the clamp notonly provides for the arcuate travel of the entire seat assembly asindicated, but permits the seat assembly to ride over obstructions orirregularities without transmitting undue strain to any part of thedevice.

Ordinarily, in the average installation, the weight of the patientschair on the lower flange of the clamp will be suflicient to hold thepivot post installation in place, but in the event such chair should besusceptible to creeping, the upper flange of the clamp may be providedwith one or more threaded openings I 26 for the reception of clampingscrews which may be tightened down against the rim of the base of the Ichair.

In accordance with the improved features of the present invention, Iprovide means for normally restraining movement of the seat from itsretracted position, in the absence of an overpowering force, and suchmeans preferably takes the form of a flat coil spring I29 encircling thesun gear and having one end anchored in said gear and its other endhooked around the lower end of the bolt 95, which is the same as beinganchored to the planetary arm 59. The spring is preferably disposed in acircumferential groove l3! formed in the gear, by anchoring one end of alength of spring wire in a recess I33 in a wall of such groove, wrappingsuch wire around the gear and then hooking its free end about the bolt95.

Any force sufficient to overcome the resistance offered by the spring,will cause the seat to move forward, the spring in the meantime beingtighter to build up a sufficient restoring force, so that upon removalof said overcoming force, the seat will be restored to its retractedposition. Under these conditions, the entire seat assembly may now beadjusted to a slight tilt angle with the vertical, say of the order of 2to 5 degrees, without the seat shifting from its retracted position. Oneof the advantages derived from this relationship resides in the factthat the weight of the operator on the seat will provide a component offorce in the forward direction of its movement, thus facilitating theuse of the seat assembly in carrying the operator toward the patient.

Working from a seat so tilted, places the operator in a more comfortableand relaxed posture, at the same time avoiding the necessity ofconsciously holding the seat against retraction by the spring, thusenabling the operator to work more efiectively and efliciently.

From the above description of my invention in its preferred form, itwill become apparent that the same fulfills all the objects of myinvention as previously stated, and while I have described my inventionin considerable detail, the same is subject to alteration andmodification without departing from the underlying principles thereof,and I, therefore, do not desire to be limited in my protection to suchdetails, except as may be necessitated by the appended claims.

I claim:

1. An adjustable seat assembly comprising wheel truck; a standardextending upwardly from said wheel truck; a seat; means supporting saidseat on said standard for movement laterally thereof; means for holdingsaid standard at a slight tilt angle with the vertical; and meansnormally restraining movement of said seat in the direction of such tiltangle from a normal unoccupied position in the absence of anoverpowering force applied to said seat and adapted to restore said seatto its normal unoccupied position upon release of such force.

2. An adjustable seat assembly comprising a wheel truck, a standardextending upwardly from said wheel truck; a seat; means supporting saidseat on said standard for movement laterally thereof; means for holdingsaid standard at a slight tilt angle with the vertical; and spring meansnormally restraining movement of said seat in the direction of such tiltangle from a normal unoccupied position in the absence of anoverpowering force applied to said seat and adapted to restore said seatto its normal unoccupied position upon release of such force.

3. An adjustable seat assembly comprising a wheel truck; a standardextending upwardly from said wheel truck; a seat; means supporting saidseat on said standard, said seat supporting means including a pair ofarms, means connecting said arms for angular movement, one with respectto the other, means pivotally mounting said arms at the free end of oneof them to said standard, and means at the free end of the other of saidarms for carrying said seat; means for holding said standard at a slighttilt angle with the vertical; and means normally restrain ing movementof said seat in the direction of such tilt angle from a normalunoccupied position in the absence of an overpowering force applied tosaid seat and adapted to restore said seat to its normal unoccupiedposition upon release of such force.

4. An adjustable seat assembly comprising a wheel truck; a standardextending upwardly from said wheel truck; a seat; means supporting saidseat on said standard for movement laterally thereof, said seatsupporting means including a pair of arms, means connecting said armsfor angular movement, one with respect to the other, means pivotallymounting said arms at the free end of one of them to said standard, andmeans at the free end of the other of said arms for carrying said seat;means for holding said standard at a slight tilt angle with thevertical; and

means normally restraining movement at said seat in the direction ofsuch tilt angle tram a normal unoccupied position inthe absence of anoverpowering force applied to said seat: and adapted to restore saidseat to its normal unoccupied position upon release oi suchforce,- saidmeans including a coil spring, one endoi which is in effect anchored tosaid standard and the other end to that arm which is pivotally connectedto said standard.

5. An adjustable seat assembly comprising a wheel truck; a standardextending upwardly from said wheeltruck; a seat; means supporting saidseat on said standard for movement laterally thereof, said seatsupporting means including a sun gear fixedly mounted at the, upper andof said standard, a planetary arm pivotally mounted at one end ontheaxisofsaid sungear and rotatable on such axis-with respectto said sungear, a planetary gear journaled' adjacent the free end of saidplanetary arm in substantially the plane of said sun gear, a seatsupporting arm, means rigidly connecting said seat supporting arm at oneend to said=planetary gear axially thereof, and a drive connectionbetween said sun gear and said planetary gear involving a chainencircling, both said gears, means for holding said standardat a slighttilt angle with the vertical; and means normally restraining movement ofsaid seat in the direction of such tilt angle from a normalunoccupied-position in the absence ofan overpoweringforce applied tosaid seat and adapted to restore saidseat to its normal unoccupiedposition upon release of such force.

6. An'adjustable seat assembly comprisinga wheel truck; a standardextending. upwardly from said wheeltruck; a seat; means supporting-saidseat on saidstandardfor movement laterally 8 thereof, said seatsupporting means including a sungear fixedly mounted at the upper end ofsaid standard, a planetary arm pivotally mounted at one end on the axisof sa-id sun gear and rotatable on such axis with respect to said sungear, a planetary gear journaled adj acent the free end of; saidplanetary arm in substantially the plane of said sun gear, a seatsupporting arm, means rigidl connecting said seat supportin arm at oneend to said planetary gear axially thereof, and a drive connectionbetween saidsun gear and said planetary gear involving a chainencircling both said gears, means for holding said standard at-aslight-tilt angle withthe vertical; and means normally restrainingmovement of said seat in the direction of such tilt angle from itsnormal unoccupied position in the absence of an overpowering forceapplied to said seat and adapted to restcresaidseat to its normalunoccupied position upon release of such force, .s-ai d meansincludingacoilspring one endoi? which is anchored to said sungear andthe other end to said planetary arm; w I r EDGAR W. MACKNIGHT.

References Cited iii the file of this patent UNITED STATES PATENTSNumber Name Date 66414'17- Richardson" May 24, 1898 972,472 niebe Oct,11, 1910 1,14'13896 Schroeder July 27, 1915 1,322,551 new Nov. 25, 19191,7*1259*2"'1 Merton May 14, 1929 21131932 Zola 1- July 27, 193':

2329?,815 Tiein pletoh Oct. 6, 1942 2 ,34551ss Volir'atlf l. Mar.28,1944

2,533,363 penalise Dec; 12, 1950 255136.120 Templeton" Feb. 19, 1952

